gammeter



Oct l 1929. J. R. GAMMETER `1,729,717

METHOD OF MAKING .BALLS Oct. 1, 1929.

Filed April 26, 1927 J. R. GAMMETER METHOD OF MAKING BALLS 2Sheets-Sheet 2 Patented Cct. l, 1929 UNITED STATES PATENT OFFICE JOHN R.GAMMETER, F AKRON, OHIO, ASSIGNOR TO A. G. SPALDING AND BROS., ACORPORATION OF NEW JERSEY METHOD or MAKING BALLS Application led April26,

This invention relates to balls comprising an inner compression elementheld under compression by an outer tension element, as in the case ofgolf balls, the strained condition of the two elements serving to givethe ball as a whole a high coeiicient of elasticity and thus to providefor a quick reiexing of the surface of the ball when the ball is struck,so that the full elastic reaction of the ball, or a large part of it,takes place while the ball is still in contact with the club, for highvelocity of the ball, and preferably before the ball has so changed itsposition with relation to the club as to cause the retiexing of the ballto spoil the accuracy of the shot.

My present invention in some of its phases is an improvement upon thatof my copending application Serial No. 186,694, filed concurrentlyherewith.

The chief objects of my present invention are to provide a highlyserviceable ball, such b as a golf ball or a tennis ball, at low cost;to

provide a highly symmetrical ball as to the distribution of its weight;and, more specifically, to provide for molding a fluid-containingball-structure to a size smaller than that which it assumes when in anuncompressed conditio prior to the molding operation.

Of the accompanying drawings:

Fig. 1 is a vertical, medial section of apparatus embodying and adaptedto carry out my invention as applied to golf balls, the moldconstituting a part of the same being shown in open condition.

Fig. 2 is a similar view showing the mold in nearly closed condition.

Fig. 3 is a vertical, medial section of a cover mold employed in thepractice of my invention in its preferred form.

Fig. 4 is an elevation, with parts sectioned and broken away, of apressure chamber such as that shown in Fig. v2. with the mold and thework therein, representing the preferred form of my invention.

Fig. 5 is a section ofthe finished ball of Fig.

Referring first to Figs. 1 and 2, the golf ball there shown comprises aresilient core or com- 1927. Serial No. 186,695.

pression member 4l() of vulcanized, soft sponge-rubber and a cover llthereon, the cover preferably being of balata or gutta percha or amixture' of those and other substitutes such as is commonly employed forgolf ball covers.

The ball is initially formed of a size substantially larger than thesize to which it is later to be molded and consequently larger than thecavity of the mold, consisting of sections 12 and 13, shown in Figs. 1and 2, with the result that when the ball at atmospheric pressure isplaced upon the lower mold section 13, as shown in Fig. 1, it is toolarge to seat therein.

To produce the ball in the condition there shown the core member 1() isfirst molded and vulcanized, with a suitable blowing agent incorpora-tedin the compound to produce the sponged condition, and the cover 11 isthen 70 applied to the vulcanized sponge core, either y applyinghemispherical or other shells of the covering material to the core andjoining them by pressure or by rolling the core upon a surface thinlycovered with the covering material in a warm condition to cause it topick up the material, or in any other suitable manner. In either casethe cover may be given a smooth and impervious exterior, if desired, bya molding operation prior to the intiroduction of the ball to theapparatus of Before the ball is placed upon the mold section 13,however, as shown in Fig. 1, if a smooth-surfaced ball is to be ina-de,the cover preferably is formed with one or more small indentions orgrooves such as those shown at 14, 14, at the part thereof which is torest upony the rim of the mold cavity, so that fluid pressure may beequalized upon all parts of the ball including that extending lnto thelower mold section.

The lower mold section 13 is 'detachably mounted in determinate positionupon tbe floor of a pressure chamber 15 and the upper 95 mold section 12is detachably mounted, by means of a dove-tail rib 16 formed thereon,upon a head 17 in which is swiveled the lower end of a screw 18 which isthreaded through the cover 19 of the pressure chamber and is 100 withaguide rib such as the rib 21 adapted to run in a complemental grooveformed in the wall of the chamber, to prevent the mold secltion fromturning with the screw 18 and to assure registry of the two moldsections. Vent apertures, such as those shown at 12a, 133,1nay be formedin the mold sections.

The pressure chamber is provided with a water inlet 22 and outlet 23 andwith an air inlet 24. y

When the ball has been formedl and mounted upon the lower mold section13 as shown in Fig. 1, the cover 19 of the pressure chamber carrying theupper mold section 12, is placed and secured upon the chamber with theupper mold member in the position there shown.

The apparatus or at least the mold sections and the ball itself aresuitably heated, as by passing hot air or an inert gas in a heatedcondition through the chamber by means of the inlet 24 and outlet 23, tosoften the cover of the'ball and to provide for its proper conformanceto the wall of the mold-cavity in the subsequent molding of the ball.Alternatively the mold-sections may be electrically heated or heatedotherwise before they are placed in the chamber, and the ball may beheated apart from theapparatus before it is introduced thereto.

With conditions as shown in Fig. 1 and with the cover of the ballsuitably softened, a fluid, preferably air or an inert gas, is con-'ducted into the chamber, the connections 22 and 23 being closed, at asufficiently high pressure to cause the ball to contract in sizeso thatit fully seats in the cavity of the lower mold section, the imperviousbut soft cover 11 contracting in circumference and transmitting theforce of the pressure fluid to the sponge rubber core and causing theair or gas contained in the cells thereof to be compressed and therubber of the cell walls to be put under strain.

When the ball has thus contracted and fallen into the lower mold cavitythe upper mold section is closed upon the ball by turning the hand-wheel20, after which the fluid pressure in the chamber is released, whereuponthe stresses in the ball, without being relieved to any greateXtent,cause the ball to expand and f completely fill the mold cavity and totake the form thereof.

While the mold remains closed a cooling fluid such as water is passedinto or through the chamber, cooling the mold and causing the cover 11of the ball to harden or set. Alternatively the cover may be composed ofa vulcanizing compound and may be vulcanized by heat received by it fromthe mold.

When the cover of the molded ball has 'thus been set, by cooling or byvulcanization or otherwise, the chamber and the mold are opened, thefinished ball is removed, and the operation as described is repeatedupon another ball.

Upon the opening of the mold and the removal of the ball therefrom'theset cover 11 sustains the force of the compressed core and is thus putunder high tension, and the compressed core and the tensioned coverfunction together to give the ball as a whole the desired highcoeiicient of elasticity, in somewhat the same manner that av pair ofleaf springs ieXed in' opposition to each other show less deflectionunder a given load than either of them alone would show.

The comparatively inextensible character of the cover material, whensuch a material is used, may prevent its elasticity from being animportant factor in the resilience of the ball under a heavy blow, andyet thecover may normally hold the core under such compression that the'distortion of the core will be small and its reiexing very quick whenthe ball is struck.

In the preferred practice of my invention'v illustrated in Figs. I v3and 4 hemispherical shells 25, 26 of the cover material are moldeddirectly in the'mold sections 12, 13 by means of a double-acting maledie 27 andthe mold sections with the shells remaining therein aretransferred to the pressure chamber 15 as shown in Fig. 4.

The male die is formed with a Huid passage 28'for passing compressed airtherethrough to separate it from the molded shells and leave the latterin the respective molddsections, a poppet valve 29 being provided ateach terminus of the passage to prevent flow of the plastic materialthereinto in the molding operation although permitting the fluid to assoutward from the male die member. olding pins 30, 30 project outwardfrom the centers of the respective poppet valves and are` adapted toproject into the vent apertures 12,

13a of the mold sections, for molding vent apertures 25a 26 (Fig. 4) inthe shells.

The mold section 13 may be provided with means, such: as the cam latches34 35, adapted to engage automatically in detent recesses 36, 37 in thesection 12, for Securing the sections together. v

After the lower mold section 13 with the shell 26 therein -has beenmounted in the chamber 15 a suitable compressible core, here -shownasconsisting of joined hemispherical bodies 31, 32 enclosing a weightingsphere 33 of lead, heavily compounded rubber or the like, is mountedupon the shell 26 as shown,

after which the cover of the chamber, carrying the mold section 12 withthe shell 25 therein, is mounted upon the chamber, pressure fluid suchas compressed air is admitted to the latter' to compress the core sothat it shrinks and fully seats in the lower shell 26, the upper moldsection is closed down to enclose the core completely in the shells andthe pressure in the chamber is then so reduced as e duced to permit thecore to expand and fill the cover, the shell being vented through theapertures 25a, 26a. The shells are then caused to Weld together, bysimply heating and cooling the mold sectlons if the cover shells are ofheat plastic but non-vulcanizing material, or by vthey are in thepressure chamber and then removed to other apparatus for the cover-Welding operation.

The vent apertures 25a, 26 are closed by the force of the expanding coreWhen the cover shells are heated.

The compressible core may be formed in numerous alternative Ways. -F orexample it may consist of a spherical shell held in a stretchedcondition by an elastic pressure Huid contained therein, so that it maybe compressed to or slightly beyond its unstrained size Withoutbuckling, or it may consist of a' spherical Winding of scrap threadrubber upon a suitable Weighting sphere such as a lead or heavilycompounded rubber ball, and enclosed in suitable sealing means such asan impervious rubber envelop or a Winding of comparatively Wide rubbertape.

A 10W temperature accelerator is of course employed Where the cover isto be vulcanized, in order to avoid heating the core material to atemperature such as to relieve the strains therein.

Many other modifications are possible Within the scope of m linventionas defined in the appended claims.

1 claim:

1. The method of making a ball which comprises molding an outer tensionelement upon an inner compression element While holding the latter undercompression by subjecting it to super-atmospheric external Huidpressure.

2. The method of making a ball which comprises forming a compressible,fluid-containing vball member, compressing said member toa smaller sizeby subjecting it to a superatmospheric external fluid pressure, andenclosing it in a mold While it is so held to small s1ze.

3. The method of making a ball which comprises forming an elasticenvelop, distending the same by internal pressure of an elastic Huid,reducing the size of the distended envelop and increasing the pressureof the fluid therein by subjecting it to a preponderating external fluidpressure, and molding a cover upon the envelop whileso holding it to re-4. The method of making. a ball which comprises forming an envelofp,distending the same by internal pressure o an elastic Iifluid,

' ternal Huid reducing the size of the distended envelop and increasingthe pressure of the fluid therein by subjectmg it to a preponderatingexternal fluid pressure, enclosing the envelop in a mold While it is soheld to reduced size, and permitting it to expand in the mold byreduction ofthe external fluid pressure.

5. The method of making a ball which comprises reducing the size of aball-forming body by applying external fluid pressure thereto andenclosing the body in a mold While it is thus held to small size.

6. The method of making a ball which comprises forming a compressiblecore, reducing the size of the core by applying expressure thereto,enclosing the core in covering elements held in sections of 'a' moldWhile the core is thus heldy to small size, reducing the pressure of theexternal fiuid and thereby permitting the core toexpand in the mold, anduniting the covering elements upon the core While they remain in themold.

I 7 The method of making a ball which consists in forming a spongerubber core, applying thereto an impervious layer of deformablematerial, reducing the size thereof by surrounding it With fluid underpressure, and fixing a strain resisting cover thereon While so heldtoreduced size.

In Witness whereof I have hereunto set my hand this 22nd day of April,1927.

JOHN R. GAMMETER.

